After I reinstalled Jenkins and Cloudbees Free Enterprise plugins, an environment variable set in my Jenkins folder stopped working and disappeared from the config UI. However, it is still there in the config.xml on the filesystem, as:
<properties>
<com.cloudbees.hudson.plugins.folder.properties.EnvVarsFolderProperty>
How should I now create environment variables that apply to an entire folder?
The functionality has been moved to the Folders Plus plugin, which requires a Jenkins Enterprise paid license.